U.S. Pat. No. 8,613,813 entitled “Forming of Metallic Glass by Rapid Capacitor Discharge” is directed, in certain aspects, to a rapid discharge heating and forming method (RDHF method), in which a metallic glass is rapidly heated and formed into an amorphous article by discharging a quantum of electrical energy through a metallic glass sample to rapidly heat the sample to a process temperature in the range between the glass transition temperature of the metallic glass and the equilibrium liquidus temperature of the metallic glass-forming alloy (termed the “undercooled liquid region”), shaping, and then cooling the sample to form an amorphous article. The above reference is incorporated herein by reference in its entirety.
U.S. Pat. No. 8,613,813 is also directed, in certain aspects, to a rapid discharge heating and forming apparatus (RDHF apparatus), which comprises a metallic glass feedstock, a source of electrical energy, at least two electrodes interconnecting the source of electrical energy to the metallic glass feedstock, where the electrodes are attached to the feedstock such that electrical connections are formed between the electrodes and the feedstock, and a shaping tool disposed in forming relation to the feedstock. In the disclosed apparatus, the source of electrical energy is configured to produce a quantum of electrical energy sufficient to heat the metallic glass sample to a processing temperature between the glass transition temperature of the metallic glass and the equilibrium liquidus temperature of the metallic glass forming alloy, while the shaping tool is configured to apply a deformational force to form the heated sample to a net shape article. In some embodiments, the source of electrical energy is configured to produce a quantum of electrical energy to heat the entirety of the sample to the processing temperature.
With respect to the electrode material, U.S. Pat. No. 8,613,813 discloses that in some embodiments the electrodes are made of a soft (i.e. low yield strength) highly-conductive metal such that when a uniform pressure is applied at the contact interface between the soft electrode and the harder metallic glass sample, any non-contact regions at the interface are plastically deformed at the electrode side of the interface, thereby improving electrical contact and reducing the electrical contact resistance. Specifically, U.S. Pat. No. 8,613,813 discloses that the electrode material is chosen to be a metal with low yield strength and high electrical and thermal conductivities, for example, copper, silver or nickel, or alloys formed with at least 95 at % of copper, silver or nickel. However, electrodes made of soft and low yield strength metals may have limited mechanical stability under typical rapid discharge heating and forming (RDHF) loads and also limited life after being repeatedly used. Therefore, there is a need for alternative electrode materials that promote good contact with the metallic glass sample leading to low electrical contact resistance, while being stable and durable under heavy loads.